Patent GB-952352-A (GB)
Title: Improvements in and relating to emulsifying agents based on silica
IPC: C09K23/00
Filed: 1960-05-19
Abstract: An emulsifying or suspending agent for oil in water emulsions or suspensions comprises SiO2 gel or sol which has not been substantially dehydrated and which has hydro- and organophilic properties due to the presence on the surface of the SiO2 of 1 or more organic cationic compounds which are (A) amines having 6-24 C atoms, i.e. NR1R2R3, where R1 is aliphatic, araliphatic, acyclic, cyclic, saturated or unsaturated hydrocarbon radical and R2 and R3 are the same or H; (B) heterocyclic nitrogeneous base, i.e. cyclic N compounds containing at least one 5- or 6-membered ring; (C) poly-alkylene imine, i.e. <FORM:0952352/C1/1> , where n is a small and x a large number and R is H, lower alkyl or hydroxyalkyl radicals; (D) hydroxyalkylpolyoxyalkylene amines, i.e. <FORM:0952352/C1/2> , where -CnH2nis a bivalent lower alkylene radical, e.g. C2-4, and R1 and R2 are H, a hydrocarbon group, <FORM:0952352/C1/3> , or together with the N atom represent a heterocyclic ring and R3 and R4 are H, a hydrocarbon group or <FORM:0952352/C1/4> and n, x and y are whole numbers; (E) carboxylic esters of (D), <FORM:0952352/C1/5> , where R is a saturated, unsaturated, cyclic, acyclic, aliphatic or aromatic hydrocarbon or substituted hydrocarbon radical or a carboxyhydrocarbon radical wherein the carboxy group is an acid, salt, ester or amide; (F) carboxylic amides of amines of the foregoing groups, i.e. RCON =, where the N is in a primary or secondary amine and R is as defined in (E); (G) products soluble in water at an acid pH which are the ester and/or amide of condensation products of mono-, di- or tri-alkylolamines with polycarboxylic acids; (H) water soluble proteins, i.e. polymeric complexes of amino-carboxylic acids; (I) quaternary ammonium compounds having at least 6 C, i.e. R4N+A-, where R is a saturated, unsaturated, cyclic, acyclic, aliphatic, aromatic or araliphatic hydrocarbon or substituted hydrocarbon group or the R groups together with N are a heterocyclic group, and A is an anion; (J) sulphonium compounds having at least 6 C, i.e. R3S+A-, where R and A are as defined in (I) or two of the R groups together with S represent a heterocyclic group.  In an example water glass (26.7% SiO2, SiO2: Na2O 3.25) was dissolved in deionized H2O and small beads of a strong acid ion-exchange resin in H form, i.e., a sulphonated cross-linked styrene-divinylbenzene resin, were added until the pH was 5.0.  The beads were filtered and aq. NaOH was added until the pH of the filtrate was 8.0, when a 3% hydrophilic SiO2 sol was formed. The organic compounds may be added as 1 or 10% solutions in H2O or xylene or in mixture with the material to be emulsified to give mixtures containing 20 parts H2O and 1.9 parts SiO2.  The pH of the mixture is adjusted to 4.5 with dilute aq. HCl or NaOH and the mixture may be homogenized. The SiO2, e.g. 0.01-30%, may be suspended in H2O and the organic compound, neat or in solution, e.g. methanol, dioxane or dimethyl formamide, may be added.  The pH of the mixture is adjusted to 2-7 for compounds from groups (A)-(H) and 2-10 for (I) and (J). A large number of preparations are described. The amount of organic compound used, e.g. 1-50%, depends on their chain length and degree of organophilicity.  Aq. suspensions of modified SiO2, e.g. 0.1-10%, can be used to prepare coarse emulsions of polymerizable liquids, e.g. aliphatic or aryl-vinyl- or -vinylidene compounds or to emulsify water insoluble liquids, e.g. hydrocarbons, halogenated hydrocarbons and ethers.ALSO:Oil-in-water emulsions are obtained with the use as emulsifier of a hydrous silica sol or gel having on the surface thereof one or more of (a) C6-24 aliphatic amines, (b) heterocyclic nitrogen bases having at least one 5- or 6-membered ring containing nitrogen, (c) polyalkylene imines containing the recurring unit -CnH2nNR- where R is hydrogen, alkyl or hydroxyalkyl, (d) hydroxyalkylpolyoxyalkylene amines (defined), (e) carboxylic esters of (d), (f) carboxylic amides of the above amines, (g) condensation products of alkylolamines and polycarboxylic acids, (h) water-soluble proteins, (i) quaternary ammonium compounds having at least 6 carbon atoms, and (j) sulphonium compounds having at least 6 carbon atoms. Emulsifiable liquids mentioned are hydrocarbons (benzene, toluene, xylene), halogenated hydrocarbons (chlorobenzene) and etters (i-propyl etter), and in Examples 15-36 the efficacy of a number of the emulsifying agents is illustrated by reference to the formation of an aqueous xylene emulsion.